The present invention relates to an adjustable continuous casting mold, and a method of adjusting a casting mold prior to, during and after casting in an effective manner. More particularly, the apparatus and method of the present invention relate to a continuous casting mold, the cross-sectional area of which can be adjusted by moving at least one of the side walls forming the mold.
Adjustable continuous casting molds for vertical casting machines are known. In these continuous casting machines, however, no sealing problems arise in the region between supply container and mold which are comparable to those of horizontal continuous casting machines for metals.
From West German Patent 26 58 242 there is known a horizontal continuous casting machine for metals which has a clamping device which is connected, on the one hand, to the mold and, on the other hand, directly to a liquid-metal conduit, a device for regulating the contact pressure of the liquid-metal conduit against the mold being provided so as to assure a tight, metal-impervious joint. This patent does not teach changing the cross-section of the mold. With respect to sealing, the device known from this patent has the disadvantage that the mount which fixes the rigid mold at its one end rests at its other end on the liquid-metal conduit. In order to absorb the forces between the liquid-metal conduit and the supply container, the rigid mold is connected via an expensive arrangement, namely foundation, base plate, bearing pedestal and displacement apparatus. The multitude of elements and the great number of possible external influences do not permit the short paths and precise adjustments of force in the region of the sealing surface which are required for an adjustable mold.
Leaking liquid metal, however, could lead to the interruption of the casting. The discontinuation of the casting has the result, in the case of a rigid mold, that solidified residual pieces remain in the mold and can only be removed with great difficulty.
It is the object of the invention to avoid the above-mentioned disadvantages and to provide a method and an apparatus for an adjustable continuous casting mold which enables a reliable changing of the passage cross-section of the mold in a structurally simple manner before, during and after the casting.
This object is obtained by providing a horizontal casting apparatus for metals, in particular steel, which comprises a liquid metal supply container having a metal outlet opening therein; a continuous casting mold adjacent the outlet of the supply container, the casting mold comprising side walls having side edges and forming a conduit having an adjustable cross-sectional area for the metal to flow therethrough; and elements for adjusting the position of at least one of the side walls parallel and transverse or perpendicular to the center axis or center line of the outlet opening thereby adjusting the cross-sectional area of the casting mold. For the sealing off of the separation area between separation ring and edge surface of the mold, adjustment elements are provided which detachably connect together the mold, forming a force-locked connection facing in the direction of the center line towards the supply container. From the contact surfaces of the side walls arranged parallel to the center line an intimate or force-locked connection is provided. Depending on the number of detachable sealing surfaces, the passage cross-section can be varied in height and width or only in height or only in width.
The change in position of the displaceable side walls is so controlled with respect to time that the most strongly stressed sealing surface in the region of the separation ring is relaxed first. In order to facilitate the starting of the displacement, the displacement force is applied in pulsating manner.
For the adjustment of the mold elements are selected which provide a high degree of reliability after the adjustment process. Depending on the requirements, adjustment apparatus with energy-storing elements (for instance springs) or self-locking elements (for instance spindles) can be used.
With the horizontal continuous casting apparatus of the present invention, only a small supply of molds is required, since the adjustable mold covers entire ranges of cross-sections. Before the casting, the variation in "thickness" or "width" can be selected by a corresponding mold.
The casting of small lots or of several casting cross-sections from a large melt is rendered possible without interrupting the casting or changing of the molds.
The adjustable mold of the invention makes it possible to adapt the mold not only to a different quality of casting but also to a different speed of casting. This adaptation is possible during the casting by adjusting the passage cross-section with simultaneous adjustment of the conicity even during the casting. This is particularly important for the beginning and ending of the casting.
The method is particularly suitable for thin casting products (thickness less than 50 mm) since the start of the process is less sensitive. This is possible since, to be on the safe side, upon the starting up a larger initial thickness can be selected which can then be corrected during casting. Only a single starting head is required in this connection for different casting cross-sections. In addition, this process is made more reliable as a whole by the longer time of filling of the mold.
The already greater reliability of the tightness resulting from the use of the adjustment elements disclosed can also be increased by shaping the sealing surfaces. Excellent sealing results are obtained when the edge surface of the side walls is developed as elements which are compressible in the region of the sealing surface and have a high restoring force, such as is true of the lip-shaped development of the front surfaces. Good results are also obtained by the combination of a straight edge surface and a seal which is operatively connected therewith, for instance a squeezable metallic seal.
As a further advantageous seal there is provided a conical sealing surface of the separation ring in the region of the displaceable side wall. In this embodiment, after the relaxation of the side wall in the direction of the center line by the pressure of the liquid casting material, the side wall is pressed, as a function of the pre-established relaxation, against the "higher" located conical part of the separation ring.
Another advantage of the horizontal continuous casting mold of the present invention becomes evident when the casting process is not properly terminated. Handling and repair after a so-called mold plug or a casting frozen in the mold are considerably facilitated by the possibility of displacing the side surfaces, in contradistinction to other non-adjustable horizontal continuous casting molds.